Vocal fry: Young Kiwi women are lowering their voices, and no one really knows why

Young women in New Zealand have started to sound a bit like Kim Kardashian, new research suggests.

Christchurch clinicians believe a type of low, rough voice known as vocal fry is becoming fashionable among middle-class women, particularly Millennials.

Their new paper, published Friday in the New Zealand Medical Journal, suggests Kardashian, Britney Spears and Bernadette from comedy show The Big Bang Theory are changing the way young women speak.

Researchers looked at overseas studies, as well as the voices of a number of Kiwi women. They found Millennial-aged Kiwi women use between two and three times as much croaky voice as those from Generation X - particularly at the end of sentences. Maori women used vocal fry more than Pakeha.

"The younger ones, born in the 1980s, were using far more vocal fry than the ones born in the 1970s," said study author Jeremy Hornibrook.

And it could spread. The study notes middle-class young women - the ones adopting vocal fry - "lead language change in new word expressions and speech sound change".

"Eventually these changes tend to be adopted by young men."

In the study, Prof Hornibrook says there has been a lot of media speculation as to why young women are increasingly lowering their voices into a croak.

In 2016, New Zealand journalist Rosemary McLeod said it was a new form of "babytalk".

"I know I'm not alone in my deep aversion to this odd development," she wrote in the Dominion Post.

"Probably most who do it, it's an unconscious behaviour," Prof Hornibrook told Newshub. "The other suggestion is that it's consciously modelled from media personalities."

Prof Hornibrook says some believe it's an attempt to sound authoritative, but others suggest it implies over-confidence.

"Paradoxically", the study notes, in general men actually prefer women with higher voices.